Improved Grab (Ex): To use this ability, a siege crab must hit an opponent at least three sizes smaller than itself with a claw attack. It can then attempt to start a grapple as a free action without provoking attacks of opportunity. If it wins the grapple check, it establishes a hold and can constrict on subsequent rounds. (A siege crab can grapple foes of larger size than indicated above, but not without provoking attacks of opportunity.)

Trample (Ex): Reflex half DC 30. The save DC is Strength-based.

Force Carapace (Su): The runes inscribed in a siege crab's shell project a field of force around the creature at all times. While its force carapace is active, a crab gains a +10 deflection bonus to Armor Class, a +8 resistance bonus on all saving throws, and immunity to magic missile spells and effects. All creatures riding within the crab's compartment gain the same benefits with regard to attacks originating outside the crab. The physical attacks of incorporeal creatures cannot bypass the force carapace, nor can such creatures pass through the crab's shell to enter or exit the inner chamber. The siege crab's claw attacks are considered force effects and can strike incorporeal creatures normally while the force carapace is in effect.

The force carapace is essentially a magic item crafted from the shell of the living creature. A dispel magic effect targeting a siege crab can suppress its force carapace for 1d4 rounds. Mordenkainen's disjunction or any other effect that destroys magic items can permanently dispel a carapace.

Shielded Compartment (Ex): Much of the interior tissue of a siege crab has been surgically removed and replaced with a sealed compartment for passengers or cargo. The compartment is accessed by a ventral hatch, and is air- and watertight. Water-breathing creatures using a siege crab can flood the compartment with seawater, while air-breathing creatures keep the chamber filled with air. The passenger space is about 10 feet by 10 feet by 10 feet; it can hold 1 large creature or 4 Medium or Small creatures.

Creatures riding within a siege crab's inner chamber have cover and concealment from opponents outside the crab when the hatch is open. While it is sealed, they instead have total cover and total concealment. The hatch is 10 feet in diameter, and the chamber's occupants can make ranged attacks from within the crab while it is open. Opening or closing the hatch is a standard action for an adjacent creature.

The death of a siege crab does not compromise the cover or concealment of passengers within its shell. However, since the crab's death usually results in it collapsing on its belly, it is difficult for occupants to exit through the hatch. Creatures trapped within the crab's carcass must cut through the tough carapace to escape; the shell has hardness 15, and breaking through it requires dealing it 30 points of damage from a slashing weapon.

Skills: A siege crab has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.

As their name implies, siege crabs are employed to attack coastal or underwater cities. In battlefield engagements, a siege crab's controller moves it directly through ranks of smaller creatures, using it to swiftly destroy enemy war machines and fortifications. The siege crab's claws make quick work of most masonry; once the city walls fall, the crab disgorges any troops it carries into the settlement's interior. After achieving its primary mission, the crab obeys its controller's next order-usually to turn and obliterate any defensive troops within sight.

The siege crab is a titanic crustacean that has been warped into a living amphibious war machine by powerful magic and skilled surgery. Kuo-toa clerics and wizards cooperated to first create them centuries ago, though reports exist of sahuagin and locathah warbands using siege crabs to raid surface settlements as well. Siege crabs are mutated from normal crabs in a process that takes decades. Each creature is magically bonded to a coral circlet, the wearer of which has absolute command over that siege crab and can give it direct verbal commands. The crab obeys these orders to the best of its ability, but unlike a construct it cannot be given conditional instructions or programs. The creature can only follow direct orders and is usually commanded to simply stand still if the controller needs to leave the crab's immediate vicinity.

A siege crab is almost 20 feet in diameter, stands 15 feet tall, and weighs over 30 tons. A siege crab does not speak but can understand simple instructions in any language given by the bearer of its coral circlet.

Aquatic Subtype

Creatures with the aquatic subtype always have swim speeds and thus can move in water without making Swim checks. An aquatic creature can breathe underwater. It cannot also breathe air unless it has the amphibious special quality.

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